The goals of the research are twofold: first, to test the claim that autistic children are specifically impaired with respect to their "theory of mind". The central finding which supports this claim is their failure on the false belief task, but it is only the hardest version of this task which has been presented to autistic children. Experiment 1 tests their ability to attribute a false belief with versions of the test which have led to success for normal 3-year-olds, a group which typically fails the standard version. The second goal of this research is to test Leslie's Metarepresentational Theory, a theory which claims that autistic children lack the innate cognitive mechanism necessary for a metarepresentational ability. Experiment 2 tests this account by using a series of tasks that compare children's understanding of mental (belief) and nonmental (photographs, drawings) representations. In all the experiments, autistic children will be compared to verbal mental age matched mentally retarded and normally developing children. The results of these studies will advance our understanding of the nature of the underlying psychological deficit in autism.